Screen Actors Guild contract chief Sallie Weaver is ankling her post as of May 1, leaving SAG without a lead negotiator heading into bargaining over its commercials contract.

Weaver has been deputy national exec director of contract for the past 4½ years, overseeing negotiation, administration and enforcement of all collective bargaining agreements. She heads the guild’s largest single division with a staff of around 200, mostly at SAG’s headquarters in Hollywood and New York.

Weaver’s worked at SAG since 1986 and previously served as deputy national exec for policy, planning and external affairs. She hasn’t yet lined up another job, and associates believe she’s likely to take a significant amount of time before making that move.

Weaver received a salary of $217,417 in the 2003-04 fiscal year, according to SAG’s filing with the Labor Dept.

Her exit underlines the ongoing turmoil at SAG, which faces an October expiration of its commercials contract with control of the national board currently in the hands of the more aggressive Membership First faction. Guild’s also in the midst of negotiations over residuals for its basic cable and cable animation contract and hasn’t reached a deal on either pact.

SAG’s outlook on the commercials contract is muddy. It hasn’t yet responded to a request by advertisers to extend the current commercials contract for a year in order to study the changing business model. And it hasn’t yet indicated if its demands for jurisdiction over product placement on TV shows will be part of those negotiations.

Weaver, who wasn’t available for comment about Thursday’s announcement, is the highest-profile SAG exec to depart following October’s firings of national exec director Greg Hessinger and three other execs, including newly hired commercial contracts director Joanne Kessler.

Those firings came after Membership First took control of the guild’s national board. Membership First campaigned last year on a platform that SAG leaders and execs such as Weaver hadn’t been assertive enough in handling negotiations on the guild’s film-TV and interactive contracts.

SAG’s still without a national exec director five months after firing Hessinger. Its search committee, headed by prexy Alan Rosenberg, has begun interviewing candidates, but a decision’s not expected immediately.

It’s not clear who will succeed Weaver, though the most likely candidate would be Tom La Grua, who’s been national director of contract strategy for the past four years.

In a statement Thursday, SAG interim national exec director Peter Frank said: “Sallie’s departure is a great loss for the guild. For two decades, she put her boundless energies and considerable talents toward protecting and enhancing the welfare of performers across America.”